25811 has 4 divisors (see below), whose sum is σ = 26352. Its totient is φ = 25272.

The previous prime is 25801. The next prime is 25819. The reversal of 25811 is 11852.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 25811 - 2⁶ = 25747 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a nialpdrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 25811.

It is not an unprimeable number, because it can be changed into a prime (25819) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 191 + ... + 296.

It is an arithmetic number, because the mean of its divisors is an integer number (6588).

2²⁵⁸¹¹ is an apocalyptic number.

25811 is a deficient number, since it is larger than the sum of its proper divisors (541).

25811 is an equidigital number, since it uses as much as digits as its factorization.

25811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 540.

The product of its digits is 80, while the sum is 17.

The square root of 25811 is about 160.6580218974. The cubic root of 25811 is about 29.5530024825.

The spelling of 25811 in words is "twenty-five thousand, eight hundred eleven".